With the development of information communications, information may be exchanged anytime and anywhere through Internet access. However, there are a number of harmful websites providing unsound information. As a risk of information leakage and hacking increases, an interest in network security is increasing.
Korean Patent Application Publication No. 2014-0044987 discloses a system and method for guiding bypass of Internet access path using domain name system (DNS) packet modulation that may enable smooth communication by preventing an Internet Protocol (IP) address collision. However, a network security system using a proxy server of the above patent application only examines and blocks an incoming packet, but does not block an outgoing packet. Accordingly, technology for providing a security service while maintaining an existing network environment is needed.
Further, there is a need for technology for giving a warning that a page is blocked without an error due to a secure sockets layer (SSL) communication even when a website to be blocked uses the SSL communication.